Effects of habitat fragmentation on the abundance of two species of Leptodactylid frogs in an Andean montane forest

We used visual transect surveys to study the effects of forest fragmentation on abundance of two species of Leptodactylid frogs in an Andean forest of northern Ecuador. We measured the abundances of Eleutherodactylus chloronatus and E. trepidotus at various distances from the forest edge in one large forest patch (200 ha) and four adjacent forest fragments (0.25-5.3 ha). We also collected data on forest characteristics (leaf litter thickness, understory density, and number and size of canopy trees) at each site. Abundance of E. chloronatus and E. trepidotus were respectively 3.5 and 2.1 times higher at sites in the large forest patch than at sites in the small fragments. Abundance of E. chloronatus was positively correlated with the log of patch size and inversely correlated with understory density E. trepidotus abundance tons not correlated with either patch size or understory density, but was inversely correlated with distance from the site to the large forest patch. The two species thus both appear to be affected by habitat fragmentation, but through different processes.